This invention relates to frame structures, and, more particularly, to a frame structure that is capable of being employed as a torque structure for providing support for the toroidal field (TF) coils of a Tokamak power reactor to minimize movement of the TF coil super conductor material during the intermittent operation of the poloidal field coils of the Tokamak power reactor by equilibrating the torque loads acting on the TF coils as close to the area of force application as feasible.
Relatively speaking, in recent years, a significant amount of attention has been directed to the potential use at some time in the future of fusion reactors as a source of power for assisting in meeting the energy needs not only of our own nation, but also those of the world in general. A requirement associated with the operation of such fusion reactors is the need to effect a suitable confinement of the plasma that is to be found present therewithin. More specifically, in accord with the mode of operation of such fusion reactors, generally speaking, it is intended that fusion reactions will occur within the plasma. Moreover, upon a realization of the proper conditions, the energy obtained as a consequence of such fusion reactions occurring in the plasma will exceed the input energy, and thereby provide useful power. However, in order to achieve such a result, basically, it is necessary that the plasma be confined in a particular region for an appreciable period of time at extremely high temperatures.
It has been recognized for some time that the employment of solid wall containers of known materials would be unsuitable for effecting the afore-referenced confinement of the plasma. Namely, even materials that are known to be resistant to the highest temperatures and that embody the greatest thermally insulative qualities would be ineffective for this purpose. Principally, this is attributable to the fact that the engagement of the plasma ions operates to produce a cooling of the plasma. Such cooling, in turn, inhibits the establishment of the conditions that are required in order for the desired fusion to occur.
As a consequence, a number of alternative methods of effecting confinement of the plasma have been examined. In this regard, attention has been directed to various schemes involving the employment of different types of magnetic and electrical field configurations. One such configuration, which has found considerable favor is that wherein a toroidal magnetic field is utilized. More specifically, this approach has given rise to a design that has been proposed by the Russians and to which the name "Tokamak" has been given. Moreover, it is to such a Tokamak device that the subject matter of the present invention principally pertains, and particularly that aspect thereof, which relates to the manner in which the support for the toroidal field (TF) coils employed therein is effected.
With regard to the matter of supporting the magnets that are found embodied in a Tokamak device, there are a number of factors to which consideration must be given. First, there is the matter of insuring that the magnets are provided with sufficient structural strength to provide the requisite degree of internal support thereto. Secondly, because of the extremely low temperatures at which these magnets are designed to operate, there is a need to accomplish the load transfer from the magnets to the support structure without experiencing excessive heat loss. Thirdly, in addition to fulfilling the requirement for internal support of the magnets, there also exists a need to provide a support structure that is capable of enabling the magnets to successfully withstand the large lateral forces that are induced on the TF coils.
Heretofore, there have been basically two types of torque structures proposed for use in Tokamak devices for purposes of providing the support required by the TF coils. For ease of reference, these two prior art types of torque structures will be referred to hereinafter as the external torque structure and the internal torque structure. Insofar as concerns the nature of construction of the external torque structure, the latter, in general, consisted of structural beams, columns, etc., located in planes above and below the TF coils, and which are connected at a good distance outside the positions of the TF coils. The internal torque structure, on the other hand, in general consisted of beams located between adjacent TF coils and positioned above and below the horizontal center plane of the Tokamak device. As taught in the prior art, the external form of torque structure, i.e., frame, is disadvantageously characterized in that such a frame interferes with the location of the diagnostics and of the other devices that are required to operate the Tokamak device. While in the case of the internal form of torque frame, there is a requirement associated with the use thereof whereby the structure of the TF coil or its case has to equilibrate the opposing moments acting on the tops and bottoms of each TF coil.
With further regard to the matter of the large lateral forces that are induced on the TF coils, the effect thereof is to create a torque in a given direction at the top of the TF coil and an equal and opposite torque at the bottom of the same TF coil. Consequently, the magnets must be suitably supported so as to enable such loads to be transmitted without producing excessive stresses or deflections. Moreover, to accomplish the latter, i.e., the transmission of the loads in the afore-referenced manner, the torque restraint must use direct load paths. On the other hand, such direct load paths for the transmission of the aforesaid loads must concomitantly enable adequate access to be had to the interior of the Tokamak device for purposes of effecting the remote maintenance of the components housed therein, i.e., maintenance on the components of the fusion reactor. Namely, although the possibility exists that access can be had to the internally housed components through the removal of structural members, it is desirable that there be present the capability for providing direct access for remotely conducting maintenance on such components without the need for removal of any structural members.
There has, thus, been evidenced in the prior art a need for an improved form of torque structure employable in a Tokamak device that would embody those features selected from both an external form of torque structure and an internal form of torque structure that serve to advantageously characterize each of the latter forms of torque structure. More specifically, there is a need to provide a design for a torque structure that would function to minimize movement of the TF coil super conductor material during the intermittent operation of the poloidal field coils that are also to be found embodied in a Tokamak device. Moreover, such a torque structure should be capable of effecting such a minimization of the afore-referenced movement by equilibrating the loads induced on the TF coils as close to the area of force application as feasible. In summary, a torque structure is desired, which provides for an inter-coil structure that exists over the area of the major out-of-plane force application to which the TF coils are subjected so as to, thus, support the TF coil structure during pulsed operation of the poloidal coils and during faulted conditions in the TF coils. Concomitant with the embodiment therein of such an intercoil structure, the proposed torque structure should desirably also possess the capability of enabling access to be had to the plasma located within the Tokamak device. Additionally, suitable provisions should be made in the proposed torque structure for equipping the latter with the requisite coolant circuits as well as the accompanying instrumentation and controls that are required to enable the low temperature differentials to be maintained between the TF coil frames, the torque structure, and the other components that are cooperatively associated therewith.
It is, therefore, an object of the present invention to provide a new and improved form of frame structure suitable for use in providing support for selected components of an operating apparatus.
It is another object of the present invention to provide such a frame structure that is employable in a fusion reactor for providing support to the means being utilized for effecting the confinement of the plasma therein.
It is still another object of the present invention to provide such a frame structure that is particularly suitable for use in a Tokamak-type device to afford support to the toroidal field (TF) coils, which the latter device embodies.
A further object of the present invention is to provide such a frame structure that is operable as a torque structure to provide support to the TF coils by equilibrating the torque loads acting on the TF coils as close to the area of force application as feasible.
A still further object of the present invention is to provide such a torque structure, which includes an intercoil structure that is designed to be affixed to a segmented, membrane shell that surrounds, encloses and supports the TF coil frames.
Yet another object of the present invention is to provide such a torque structure that is characterized in that it still permits adequate access to be had to the interior of the Tokamak-type device for purposes of accomplishing remote maintenance on components housed internally therein.
Yet still another object of the present invention is to provide such a torque structure which is relatively less costly to provide that prior art forms of torque structures, that is advantageously characterized in that it embodies the desirable features of both external and internal forms of torque structures, and yet remains capable of providing the requisite degree of support to the TF coils of a Tokamak-type device.